Oxygen is commonly administered to living organisms, and in particular, humans, for medical and survival purposes. For example, a significant population of humans require administration of supplemental oxygen to alleviate respiratory disorders, such as COPD. Such supplemental oxygen is traditionally supplied by compressed or liquid oxygen cylinders. However, more recently, in situ PSA medical oxygen concentrators for individual use have been developed, and are being used in such environments as residential homes and during travel for mobile applications.
Some examples of known concentrators are described in: U.S. Pat. No. 7,121,276 B2 to Jagger et al. (2006) for “Personal Oxygen Concentrator”; U.S. Pat. No. 6,551,384 B1 to Ackley and Zhong (2003) for “Medical Oxygen Concentrator”; and U.S. Pat. No. 5,827,358 to Kulish and Swank (1998) for “Rapid Cycle Pressure Swing Adsorption Oxygen Concentrator Method and Apparatus”; and International Publication No.: WO 2006/044172 A2 to McCombs et. al. (2006) for “Mini-Portable Oxygen Concentrator.”
It has been a longstanding goal of oxygen concentrator designers to reduce adsorber size, while still providing for production of ˜2-8 liters/minute of about ˜90-93% pure O2 from ambient air for home or hospital medical use. In seeking to accomplish that objective, one could employ any number of mechanisms, for instance, cyclic adsorptive process such as Pressure Swing Adsorption (PSA), Vacuum Swing Adsorption (VSA), or Pressure-Vacuum Swing Adsorption (PVSA), and by employing a N2 selective zeolite adsorbent. Despite the theories and available technology, nonetheless, this long-standing critical goal for the industry remains unmet. As described above, numerous patents have been issued which describe various process designs to approach this goal by manipulating the type of the adsorbent used, the synthesis of the process cycle steps, the total process cycle time, the adsorber and valving design, etc. One popular approach is to reduce the process cycle time so that the adsorbent is used more frequently, thereby increasing its specific O2 productivity rate. Cycle times of few minutes (large commercial oxygen generators) to few seconds (small medical oxygen generators) are generally used. Cycle time of a fraction of a second has also been claimed.
Despite the existence of such oxygen concentrator technology described in the literature, there exists a continuing and unmet need for even smaller, and preferably miniature, efficient, oxygen concentrator apparatus and systems that are suitable for individual use, both in terms of size and performance, as well as in terms of cost. Further, there is a need for miniature oxygen concentrators that can snap on or otherwise be installed on existing compressed air lines to provide a ready source of oxygen without the need for air compressor, air blower and/or vacuum pumps and other heavy components to provide oxygen having a purity of more than about 90%.